fbdev: sh_mobile_meram: Fix defined but not used compiler warnings

If both CONFIG_PM_SLEEP and CONFIG_PM_RUNTIME are not set:

drivers/video/sh_mobile_meram.c:573: warning: ‘sh_mobile_meram_suspend’ defined but not used
drivers/video/sh_mobile_meram.c:597: warning: ‘sh_mobile_meram_resume’ defined but not used

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>